linux-kernel - Re: [PATCH RESEND v3 1/3] ACPI: battery: Simplify battery hook locking

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Message-ID: <CAJZ5v0geqx92+XG-yxXnBFUeNBBygwvAbkxPBEtKi6f88_RYJA@mail.gmail.com>
Date: Wed, 2 Oct 2024 14:06:45 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Armin Wolf <W_Armin@....de>
Cc: pali@...nel.org, dilinger@...ued.net, rafael@...nel.org, lenb@...nel.org, 
	hdegoede@...hat.com, ilpo.jarvinen@...ux.intel.com, 
	platform-driver-x86@...r.kernel.org, linux-acpi@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v3 1/3] ACPI: battery: Simplify battery hook locking

On Tue, Oct 1, 2024 at 11:28 PM Armin Wolf <W_Armin@....de> wrote:
>
> Move the conditional locking from __battery_hook_unregister()
> into battery_hook_unregister() and rename the low-level function
> to simplify the locking during battery hook removal.
>
> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Reviewed-by: Rafael J. Wysocki <rafael@...nel.org>

Well, "looks good to me" doesn't usually mean "Reviewed-by", but you
can retain the tag in this particular case.

But in the future please don't add Reviewed-by or Acked-by tags from
people to patches if you have not actually received those tags.

> Reviewed-by: Pali Rohár <pali@...nel.org>
> Signed-off-by: Armin Wolf <W_Armin@....de>
> ---
>  drivers/acpi/battery.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index f4599261cfc3..dda59ee5a11e 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -703,28 +703,28 @@ static LIST_HEAD(acpi_battery_list);
>  static LIST_HEAD(battery_hook_list);
>  static DEFINE_MUTEX(hook_mutex);
>
> -static void __battery_hook_unregister(struct acpi_battery_hook *hook, int lock)
> +static void battery_hook_unregister_unlocked(struct acpi_battery_hook *hook)
>  {
>         struct acpi_battery *battery;
> +
>         /*
>          * In order to remove a hook, we first need to
>          * de-register all the batteries that are registered.
>          */
> -       if (lock)
> -               mutex_lock(&hook_mutex);
>         list_for_each_entry(battery, &acpi_battery_list, list) {
>                 if (!hook->remove_battery(battery->bat, hook))
>                         power_supply_changed(battery->bat);
>         }
>         list_del(&hook->list);
> -       if (lock)
> -               mutex_unlock(&hook_mutex);
> +
>         pr_info("extension unregistered: %s\n", hook->name);
>  }
>
>  void battery_hook_unregister(struct acpi_battery_hook *hook)
>  {
> -       __battery_hook_unregister(hook, 1);
> +       mutex_lock(&hook_mutex);
> +       battery_hook_unregister_unlocked(hook);
> +       mutex_unlock(&hook_mutex);
>  }
>  EXPORT_SYMBOL_GPL(battery_hook_unregister);
>
> @@ -750,7 +750,7 @@ void battery_hook_register(struct acpi_battery_hook *hook)
>                          * hooks.
>                          */
>                         pr_err("extension failed to load: %s", hook->name);
> -                       __battery_hook_unregister(hook, 0);
> +                       battery_hook_unregister_unlocked(hook);
>                         goto end;
>                 }
>
> @@ -804,7 +804,7 @@ static void battery_hook_add_battery(struct acpi_battery *battery)
>                          */
>                         pr_err("error in extension, unloading: %s",
>                                         hook_node->name);
> -                       __battery_hook_unregister(hook_node, 0);
> +                       battery_hook_unregister_unlocked(hook_node);
>                 }
>         }
>         mutex_unlock(&hook_mutex);
> @@ -837,7 +837,7 @@ static void __exit battery_hook_exit(void)
>          * need to remove the hooks.
>          */
>         list_for_each_entry_safe(hook, ptr, &battery_hook_list, list) {
> -               __battery_hook_unregister(hook, 1);
> +               battery_hook_unregister(hook);
>         }
>         mutex_destroy(&hook_mutex);
>  }
> --
> 2.39.5
>